Systems and Methods for Integrated Shielding in a Current Sensor

ABSTRACT

Systems and methods described herein are directed towards integrating a shield layer into a current sensor to shield a magnetic field sensing element and associated circuitry in the current sensor from electrical, voltage, or electrical transient noise. In an embodiment, a shield layer may be disposed along at least one surface of a die supporting a magnetic field sensing element. The shield layer may be disposed in various arrangements to shunt noise caused by a parasitic coupling between the magnetic field sensing element and the current carrying conductor away from the magnetic field sensing element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of and claims the benefitof and priority to U.S. patent application Ser. No. 15/363,285, filed onNov. 29, 2016, which application is incorporated by reference herein inits entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

BACKGROUND

As is known in the art, some current sensors use a magnetic fieldsensing element in proximity to a current conductor. The sensing elementcan generate an output signal having a magnitude proportional to themagnetic field induced by a current that flows through the currentconductor.

Various parameters characterize the performance of current sensors,including sensitivity. Sensitivity is related to the magnitude of achange in output voltage from the sensing element in response to asensed current. The sensitivity of a current sensor can be influenced bya variety of factors, including is a physical distance between thesensing element and the conductor.

Integration of the current sensor, including the sensing element and theconductor into an integrated circuit (IC) package calls for close andprecise positioning of the current conductor relative to the sensingelement. Thus, voltage noise that is capacitively coupled from thecurrent conductor can adversely impact the performance and output of thesensing element and the current sensor causing an unwanted or inaccurateresponse.

SUMMARY

Systems and methods described herein are directed towards integrating ashield layer into a current sensor. In an embodiment, noise fromexternal sources and internal sources, such as between differentcomponents of the current sensor, can impact the output and performanceof the current sensor. For example, in a current sensor, having a diesupporting a magnetic field sensing element and associated circuitry anda current carrying conductor (e.g. lead frame), the die and the currentcarrying conductor can form two plates of a parasitic capacitor. Thiscapacitance can lead to the coupling of electrical, voltage, orelectrical transient noise from the conductor to the die during largetransient (dV/dt) events on the conductor. In an embodiment, the shieldlayer can be disposed in various arrangements between the die and theconductor to shunt this noise to ground, for example, when one plate ofthe capacitor is tied to ground through the shield layer.

In an embodiment, the shield layer may be disposed along at least onesurface of a die supporting a magnetic field sensing element to shieldthe magnetic field sensing element and associated circuitry fromexternal noise and internal noise, such as may be capacitively coupledfrom a current carrying conductor in the current sensor. In anembodiment, the shield layer may be disposed in various arrangements toreduce the effect of parasitic coupling between the magnetic fieldsensing element and the current carrying conductor. In some embodiments,having a die up configuration, a shield layer may be disposed along aback side of the die and proximal to the current carrying conductor.

In other embodiments, such as those having a flip chip configuration, ashield layer may be disposed on a surface of the die supporting themagnetic field sensing element proximate to the current carryingconductor. The shield layer may include an aperture (or other featuresto enable high frequency magnetic fields to reach the sensing element)to reduce eddy currents. In some embodiments having a dual die assembly,a first die may be disposed between the current carrying conductor and asecond die supporting the magnetic field sensing element. The first diemay include shield and insulation layers to reduce a noise experiencedby the magnetic field sensing element and circuitry.

The shield layer can be integrated into the current sensor using varioustechniques, including but not limited to, through hole silicon vias,stacked die arrangements, and/or wafer bonding, and be configured toprevent coupling noise onto the die during high transient (dV/dt) eventsin the current carrying conductor.

In a first aspect, the present disclosure is directed towards a currentsensor having a conductor, an insulation layer in contact the conductor,a semiconductor substrate having a shield layer disposed on a firstsurface proximal to the insulation layer and a second opposing surfacedistal from the insulation layer and a via extending through thesemiconductor substrate to couple the shield layer to the second surfaceof the semiconductor substrate. In some embodiments, the shield layercan be coupled to a reference potential through the via.

In an embodiment, the current sensor can be provided in the form of anintegrated circuit having a lead frame. The conductor may comprise afirst portion of the lead frame and a plurality of signal leads maycomprise a second portion of the lead frame. The current sensor mayinclude an interconnect configured to couple the via to at least one ofthe plurality of signal leads. In some embodiments, the interconnect mayinclude a wire bond.

In an embodiment, the shield layer can be coupled to a referencepotential of a magnetic field sensing circuit supported by the secondsurface of the semiconductor substrate. The magnetic field sensingcircuit may include a magnetic field sensing element comprising at leastone of a Hall-effect element or a magnetoresistance element. Theinsulation layer may include at least one of a polyimide film or a layerof adhesive. The shield layer may include at least one of copper,aluminum or gold, etc.

In some embodiments, the via comprises a through-silicon via extendingfrom the first surface of the semiconductor substrate to the secondsurface of the semiconductor substrate.

In an embodiment, the first surface of the semiconductor substrate maysupport a magnetic field sensing circuit. The magnetic field sensingcircuit may include a magnetic field sensing element comprising at leastone of a Hall-effect element or a magnetoresistance element. The shieldlayer may include an aperture aligned with the magnetic field sensingelement.

In another aspect, the present disclosure is directed towards a currentsensor having a conductor and a first die having a first surfaceproximal to the conductor and a second opposing surface distal from theconductor. The first die may include a shield layer. The current sensormay further include a second die having a first surface proximal to thefirst die and a second opposing surface distal from the first die andsupporting a magnetic field sensing circuit.

In an embodiment, the first die may include a semiconductor substratehaving first and second opposing surfaces, a protective layer having afirst surface proximal to the second surface of the semiconductorsubstrate and having a second opposing surface, the shield layer havinga first surface proximal to the second surface of the protective layerand having a second opposing surface and a first insulation layer havinga first surface proximal to the second surface of the shield layer andhaving a second opposing surface. In some embodiments, a bond pad may bein contact with the shield layer and exposed through an aperture in thefirst insulation layer.

In an embodiment, the current sensor may be provided in the form of anintegrated circuit having a lead frame. The conductor may comprise afirst portion of the lead frame and a plurality of signal leads maycomprise a second portion of the lead frame and the current sensor mayfurther comprise a wire bond coupled between the bond pad and at leastone of the signal leads.

In some embodiments, the semiconductor substrate may include silicon.The protective layer may include silicon oxide, silicon dioxide, or acombination thereof. The shield layer may include at least one ofcopper, aluminum or gold. The first insulation layer may includebenzo-cyclobutene (BCB).

In some embodiments, the magnetic field sensing circuit may include amagnetic field sensing element comprising at least one of a Hall-effectelement or a magnetoresistance element. The first die may include asecond insulation layer disposed between the conductor and thesemiconductor substrate. In an embodiment, the second insulation layermay include a flex circuit having a layer of Kapton® and a metalizedlayer. The second insulation layer may include at least one of apolyimide film or a layer of adhesive.

In an embodiment, the first die may be larger than the conductor andhave at least one edge that extends beyond an edge of the conductor. Thecurrent sensor may be provided in the form of an integrated circuithaving a lead frame. The conductor may include a first portion of thelead frame and a plurality of signal leads may include a second portionof the lead frame, and the at least one edge of the first die may extendbeyond an edge of at least one of the signal leads. In some embodiments,a first epoxy layer disposed between the conductor and the first surfaceof the first die and a second epoxy layer disposed between the secondsurface of the first die and the first surface of the second die.

In another aspect, the present disclosure is directed towards a currentsensor having a conductor, an insulation layer in contact with theconductor, a shield layer comprising at least one of a metalized tape ora metalized Mylar® spaced from the conductor by the insulation layer anda semiconductor substrate having a first surface disposed proximal tothe shield layer and a second opposing surface disposed distal from theshield layer and supporting a magnetic field sensing element.

The magnetic field sensing element may include at least one of aHall-effect element or a magnetoresistance element. The current sensormay be provided in the form of an integrated circuit having a leadframe. The conductor may include a first portion of the lead frame and aplurality of signal leads may include a second portion of the leadframe. In some embodiments, the current sensor may include a wire bondconfigured to couple the shield layer to at least one of the pluralityof signal leads.

In an embodiment, the current sensor may include a via extending throughthe semiconductor substrate to couple the shield layer to the secondsurface of the semiconductor substrate. The current sensor may includean interconnect configured to couple the via to at least one of theplurality of signal leads.

In some embodiments, the current sensor may include a conductive epoxydisposed between the shield layer and the semiconductor substrate andalong at least one side of the semiconductor substrate between the firstand second surfaces of the substrate.

In another aspect, the present disclosure is directed towards a currentsensor having a first die having a first surface and a second opposingsurface supporting a conductor in the form of a coil and a second diehaving a first surface on which a shield layer is formed and a secondopposing surface. The shield layer may include an aperture configured toreduce eddy currents and the shield layer may be spaced from the secondsurface of the first die by an airgap. The aperture (e.g., cuts, slits,slots or other similar features) may enable high frequency magneticfields to reach the sensing element.

In some embodiments, the shield layer comprises a first shield layer andthe second die may include a protective layer having a first surfaceproximal to the first shield layer and a second opposing surface, asemiconductor substrate having a first surface proximal to theprotective layer and a second opposing surface, and a second shieldlayer having a first surface proximal to the semiconductor substrate anda second opposing surface.

In an embodiment, the protective layer may support the magnetic fieldsensing element. The magnetic field sensing element comprises at leastone of a Hall-effect element or a magnetoresistance element. The firstdie may include a third shield layer proximal to the first surface ofthe first die.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features may be more fully understood from the followingdescription of the drawings in which:

FIG. 1 is a cross section of a current sensor having a die up assemblywith a back side die shield layer and a through silicon via;

FIG. 2 is a cross section of a current sensor having a die up assembly,back side die shield layer and a through silicon via with directbonding;

FIG. 3 is a cross section of a current sensor having a die downassembly, a top shield layer, and a through silicon via;

FIG. 3A is a diagram of a bottom surface of shield layer having aplurality of slots;

FIG. 4 is a cross section of a current sensor having a dual dieassembly;

FIG. 5 is a cross section of a current sensor having a dual die assemblyand a second insulation layer between a conductor and a first die;

FIG. 6 is a cross section of a current sensor having a floating backside shield layer;

FIG. 7 is a cross section of a current sensor having a bonded back sideshield layer;

FIG. 8 is a cross section of a current sensor having a back side shieldlayer and a through silicon via to couple the shield layer to areference potential;

FIG. 9 is a cross section of a current sensor having a back side shieldlayer and a conductive epoxy formed along at least one side of asemiconductor substrate; and

FIG. 10 is a cross section of a current sensor having a flip chipassembly with a coil as a conductor supported by a first die.

DETAILED DESCRIPTION

Before describing the present invention, some introductory concepts andterminology are explained.

As used herein, the term “magnetic field sensing element” is used todescribe a variety of electronic elements that can sense a magneticfield. The magnetic field sensing element can be, but is not limited to,a Hall-effect element, a magnetoresistance element, or amagnetotransistor. As is known, there are different types of Hall-effectelements, for example, a planar Hall element, a vertical Hall element,and a Circular Vertical Hall (CVH) element. As is also known, there aredifferent types of magnetoresistance elements, for example, asemiconductor magnetoresistance element such as Indium Antimonide(InSb), a giant magnetoresistance (GMR) element, for example, a spinvalve, an anisotropic magnetoresistance element (AMR), a tunnelingmagnetoresistance (TMR) element, and a magnetic tunnel junction (MTJ).The magnetic field sensing element may be a single element or,alternatively, may include two or more magnetic field sensing elementsarranged in various configurations, e.g., a half bridge or full(Wheatstone) bridge. Depending on the device type and other applicationrequirements, the magnetic field sensing element may be a device made ofa type IV semiconductor material such as Silicon (Si) or Germanium (Ge),or a type III-V semiconductor material like Gallium-Arsenide (GaAs) oran Indium compound, e.g., Indium-Antimonide (InSb).

As is known, some of the above-described magnetic field sensing elementstend to have an axis of maximum sensitivity parallel to a substrate thatsupports the magnetic field sensing element, and others of theabove-described magnetic field sensing elements tend to have an axis ofmaximum sensitivity perpendicular to a substrate that supports themagnetic field sensing element. In particular, planar Hall elements tendto have axes of sensitivity perpendicular to a substrate, while metalbased or metallic magnetoresistance elements (e.g., GMR, TMR, AMR) andvertical Hall elements tend to have axes of sensitivity parallel to asubstrate.

As used herein, the term “magnetic field sensing circuit” is used todescribe a circuit that uses a magnetic field sensing element, generallyin combination with other circuits. Magnetic field sensing circuits areused in a variety of applications, including, but not limited to, anangle sensor that senses an angle of a direction of a magnetic field, acurrent sensor that senses a magnetic field generated by a currentcarried by a current-carrying conductor, a magnetic switch that sensesthe proximity of a ferromagnetic object, a rotation detector that sensespassing ferromagnetic articles, for example, magnetic domains of a ringmagnet or a ferromagnetic target (e.g., gear teeth) where the magneticfield sensor is used in combination with a back-biased or other magnet,and a magnetic field sensor that senses a magnetic field density of amagnetic field.

Referring to FIG. 1, a current sensor 100 is provided with a shieldlayer 120 to reduce the effects of electrical, voltage, or electricaltransient noise coupled to active circuitry within the current sensor100 through parasitic capacitance between a conductor portion and thecircuitry. The current sensor 100 includes a conductor 140, aninsulation layer 130 in contact with the conductor 140 and asemiconductor substrate 110 having a shield layer 120 disposed on afirst surface 110 a proximal to the insulation layer 130 and a secondopposing surface 110 b distal from the insulation layer 130. The currentsensor 100 further includes a magnetic field sensing circuit, includinga magnetic sensing element 115, supported by the semiconductor substrate110 and a via 150 extending through the semiconductor substrate 110 tocouple the shield layer 120 to the second surface 110 b of thesemiconductor substrate 110. In an embodiment, the shield layer 120 maybe coupled to a reference potential.

In an embodiment, current sensor 100 has a die up configuration. Die upassembly may refer to a current sensor having a magnetic field sensingelement 115 and associated circuitry on a surface (here a top surface110 b) of the substrate 110 distal from the current conductor 140. Forexample, and still referring to FIG. 1, a first surface 110 a of thesemiconductor substrate 110 is disposed on the shield layer 120 andproximal to the conductor 140. A second surface 110 b supports amagnetic field sensing element 115 and is distal from the conductor 140.Thus, the second surface 110 b may be referred to as an active surfaceand the first surface 110 a may be referred to as a back surface.

The magnetic field sensing element 115 may be diffused into the secondsurface 110 b or otherwise disposed on or supported by the secondsurface 110 b. While only one magnetic field sensing element 115 isshown, it should be appreciated that more than one magnetic fieldsensing element 115 may be used in current sensor 100.

The magnetic field sensing element 115 may include a Hall-effect elementor magnetoresistance elements. For example, the magnetoresistanceelements may include at least one of Indium Antimonide (InSb), a giantmagnetoresistance (GMR) element, an anisotropic magnetoresistance (AMR)element, a tunneling magnetoresistance (TMR) element or a magnetictunnel junction (MTJ) element. The magnetoresistance elements can bevery sensitive and therefore, in some embodiments, the die up assemblydesign may be used for current sensors 100 having a magnetoresistanceelement to create a larger distance between the magnetoresistanceelement and a current carrying conductor 140.

In some embodiments, during manufacture of the current sensor 100, themagnetoresistance element 115 may be deposited on a silicon layer aspart of a final processing step making a top layer metal shield(adjacent to the second active surface 110 b), difficult to accomplishwithout damaging the magnetoresistance element. Thus, the use of thebackside shield layer 120 disposed between the semiconductor substrate110 and the insulation layer 130 (and before the magnetic field sensingelement 115), allows for a metal shield layer to be added to the currentsensor 100 without damaging the magnetoresistance element.

In an embodiment, the current sensor 100 may be provided as anintegrated circuit (IC) having a lead frame. The lead frame may have twoportions, a first portion for carrying a primary current to be detectedand a second portion for carrying signals to and from the currentsensor. For example, the first portion of the lead frame may provide theconductor 140 and the second portion of the lead frame may comprise aplurality of signal leads 145.

The lead frame may be formed from various materials and by varioustechniques, such as stamping or etching. As one example, the lead frameis a copper lead frame pre-plated with NiPdAu. Other suitable materialsfor the lead frame include but are not limited to aluminum, copper,copper alloys, titanium, tungsten, chromium, Kovar™, nickel, or alloysof the metals. Furthermore, the lead frame may be comprised of anon-conductive substrate material, such as a standard PC board with FR-4and copper traces, or a Kapton material with copper or other metaltraces (for example a flexible circuit board). The lead and lead framedimensions can be readily varied to suit particular applicationrequirements.

The substrate 110 may be electrically coupled to at least one signallead 145 (i.e. lead frame) through an interconnect 160. In someembodiments, the second active surface 110 b may be coupled to a signallead 145 through the interconnect 160. In an embodiment, theinterconnect 160 may be a wire bond coupled between a bond pad on thesecond active surface 110 b and the signal lead 145, as shown.

The shield layer 120 can be disposed over or under the first surface 110a (e.g. backside metal shield) of the semiconductor substrate 110. Insome embodiments, the shield layer 120 may be applied to or otherwisecoated on the first surface 110 a of the substrate 110. For example, theshield layer 120 may be plated on the first surface 110 a. In otherembodiments, the shield layer 120 may be formed on the insulation layer130 and the substrate 110 attached to the shield layer 120.

In operation, the shield layer 120 which is electrically coupled to areference potential, serves to tie one plate of undesirable parasiticcapacitance between the conductor 140 and substrate 110 to the referencepotential. As described herein, a reference potential may refer to areference voltage including but not limited to a supply voltage (e.g.,Vcc), a DC voltage, output voltage or a ground voltage. For example, inone embodiment, the reference potential may couple shield layer 120 to afixed voltage such that noise is absorbed. The shield layer 120 mayinclude a conductive material, for example and without limitation,aluminum, copper, gold, nickel, aluminum, aluminum copper alloy or otherconductive metal material.

The insulation layer 130 can be disposed over a first surface of theconductor 140 and between the shield layer 120 and the conductor 140. Insome embodiments, the insulation layer 130 may be applied to a firstsurface (e.g., top surface) of the conductor 140 as part of amanufacturing process of the current sensor 100. The insulation layer130 may be applied such that it extends beyond a length of the firstsurface of the conductor 140. For example, a first and/or second edge ofthe insulation layer 130 may extend beyond a first and/or second edge(e.g., a length) of the conductor 140, the shield layer 120 or thesubstrate 110 or a combination of them or all of them.

In an embodiment, the insulation layer 130 may extend beyond a length ofthe conductor 140, shield layer 120 and/or substrate 110 for creepageand clearance reasons. The term “clearance” refers to the shortestdistance through air between two conductive parts such as the primaryand secondary leads. The term “creepage” refers to the shortest distancebetween two conductive parts along the surface of any insulationmaterial common to both parts. The spacing distance between componentsthat are required to withstand a given working voltage may be specifiedin terms of creepage and clearance. Thus, in some embodiments, to meet aspecific standard or need of a particular application of the currentsensor 100, the insulation layer 130 may extend beyond a length of theconductor 140, shield layer 120 and/or substrate 110 to meet a clearanceand/or creepage requirement and increase a distance between twoconductive parts (e.g., conductor 140, substrate 110) of the currentsensor 100. The length or distance by which the insulation layer 130extends beyond a length of the conductor 140, shield layer 120 and/orsubstrate 110 may vary based on a particular application.

The insulation layer 130 may include a polymer dielectric material. Forexample, the polymer dielectric material may include a polyimide film, alayer of adhesive material or a combination of polyimide film andadhesive material. In some embodiments, the current sensor 100 mayinclude one or more insulation layers 130. For example, the layer ofadhesive material may include a tape material with an additionaladhesive layer (e.g., nonconductive epoxy, die attach paste) disposedover it to couple to shield layer 120. The one or more layers of theinsulation layer 130 may include different materials. In otherembodiments, each of the multiple insulation layers 130 may include thesame materials.

In some embodiments, the insulation layer 130 may be formed with ataping process. In other embodiments, the lead frame insulation layer130 may be formed with a deposition process, such as on the substrate110. The deposition process used to form the insulation layer 130 caninclude a variety of processes, including, but not limited to, a screenprinting process, a spin depositing process, a sputtering process, aplasma enhanced chemical vapor deposition (PECVD) process, and alow-pressure chemical vapor deposition (LPCVD) process. The screenprinting process can result in a substrate insulating layer comprised ofa variety of materials, including but not limited to, polymer or ceramicmaterials. The spin depositing process can result in a substrateinsulting layer comprised of a variety of materials, including but notlimited to a polymer dielectric film, for example, polyimide (e.g.,trade name Pyralin®) or bisbenzocyclobutene (BCB) (e.g., trade nameCyclotene®). The sputtering process can result in the insulting layer130 comprised of a variety of materials, including but not limited to,nitride or oxide. The PECVD process can result in the insulting layer130 comprised of a variety of materials, including but not limited to,nitride or oxide. The LPCVD process can result in the insulting layer130 comprised of a variety of materials, including but not limited to,nitride or oxide.

In an embodiment, the substrate 110 may be mounted or otherwise attachedto the conductor 140. The substrate 110 may be mounted after the shieldlayer 120 has been applied to the first surface 110 a of the substrate110 and after the insulation layer 130 has been applied to the firstsurface of the conductor 140. Thus, the shield layer 120 can be mountedon or otherwise disposed on the insulation layer 130 and make contactwith the insulation layer 130. In an embodiment, the substrate 110 maybe separated from the conductor 140 by at least the shield layer 120 andthe insulation layer 130.

In an embodiment, to couple the shield layer 120 to a referencepotential and/or at least one signal lead 145, a via 150 can be formedin the semiconductor substrate 110. The via 150 may be a through-siliconvia and can extend through the semiconductor substrate 110, from thefirst surface 110 a to the second surface 110 b. In some embodiments,the via 150 may couple the shield layer 120 to the second surface 110 b(i.e. active surface) of the semiconductor substrate 110 and/or to areference potential of a magnetic field sensing circuit supported by thesecond substrate surface 110 b.

In an embodiment, the via 150 can be coupled to a reference potential,as mat be a reference potential associated with a magnetic field sensingcircuit supported by the substrate 110. The via 150 may be coupled tothe reference potential to tie a plate of the parasitic capacitancebetween the substrate 110 and the conductor 140 to the referencepotential. Thus, a path may be established to shunt interfering coupling(internal noise) due to high transient events to the referencepotential.

Now referring to FIG. 2, a current sensor 200 is provided with a shieldlayer 220 to reduce the effects of electrical, voltage, or electricaltransient noise coupled to the active circuitry of the current sensor200 through the parasitic capacitance between a conductor portion andthe circuitry. The current sensor 200 includes a conductor 240, aninsulation layer 230 in contact with the conductor 240 and asemiconductor substrate 210 having a shield layer 220 disposed on afirst surface 210 a proximal to the insulation layer 230 and a secondopposing surface 210 b distal from the insulation layer 230. The currentsensor 200 further includes a magnetic field sensing circuit, includinga magnetic field sensing element 215, supported by the semiconductorsubstrate 210 and a via 250 extending through the semiconductorsubstrate 210 to couple the shield layer 220 to the second surface 210 bof the semiconductor substrate 210. In an embodiment, the shield layer220 may be coupled to a reference potential (e.g., a reference voltage,a supply voltage, a DC voltage, ground voltage).

The current sensor 200 may have a die up assembly having the magneticfield sensing element 215 and associated circuity on a surface (here atop, second surface 210 b) of the substrate 210 distal from the currentconductor 210. The semiconductor substrate 210 has a first surface 210 adisposed proximal to the conductor 240 and a second surface 210 b thatsupports a magnetic field sensing element 215, which is distal from theconductor 240. In some embodiments, the second surface 210 b may bereferred to as an active surface and the first surface 210 b may bereferred to as a backside surface.

In an embodiment, the magnetic field sensing element 215 may include aHall-effect element or a magnetoresistance element. For example, themagnetoresistance elements may include at least one of Indium Antimonide(InSb), a GMR element, an AMR element, a TMR element or a MTJ element.

The magnetic field sensing element 215 may be diffused into the secondsurface 210 b or otherwise disposed on or supported by the secondsurface 310 b. While only one magnetic field sensing element 215 isshown, it should be appreciated that more than one magnetic fieldsensing element 215 may be used in current sensor 200.

The current sensor 200 may be provided as an IC having a lead frame. Thelead frame may have a first portion for carrying a primary current to bedetected and a second portion for carrying signals to and from thecurrent sensor 200. The first portion of the lead frame may provide theconductor 240 and the second portion may comprise a plurality of signalleads 245.

The substrate 210 may be electrically coupled to at least one signallead 245 (i.e., lead frame) through an interconnect 260. In someembodiments, the second active surface 210 b may be coupled to a signallead 245 through the interconnect 260. The interconnect 260 may be awire bond coupled between a bond pad on the second surface 210 b and thesignal lead 245. For example, a bond pad may be formed on or disposed onthe second surface 210 b and connected to the interconnect 260 to coupleto signal lead 245.

In the illustrative embodiment of FIG. 2, the shield layer 220 isdisposed along the first surface 210 a and distal from the magneticfield sensing element 215, thus this assembly may be referred to as backside die shield. The shield layer 220 may be applied to or otherwisecoated on the first surface 210 a of the substrate 210. For example, theshield layer 220 may be plated to the first surface 210 a. In otherembodiments, the shield layer 220 may be disposed on the insulationlayer 230 and the substrate 210 may be disposed on the shield layer 220.

In operation, the shield layer 220, which is electrically coupled to areference potential, serves to tie one plate of undesirable parasiticcapacitance between the conductor 240 and substrate 210 to the referencepotential (e.g., ground). The shield layer 220 may include a conductivematerial, for example and without limitation, aluminum, copper, gold,nickel, aluminum copper alloy or other conductive metal material.

The shield layer 220 may be coupled to a reference potential of amagnetic field sensing circuit supported by the second surface 210 b ofthe semiconductor substrate 210. For example, the via 250 may extendthrough the semiconductor substrate 210 to couple the shield layer 220to the second surface 210 b of the semiconductor substrate 210. The via250 may be formed within the substrate 210. The via 250 may be athrough-silicon via and extend from the first surface 210 a to thesecond surface 210 b.

In some embodiments, the shield layer 220 can be coupled to thereference potential (e.g., signal lead 245) through the via 250. In anembodiment, the via 250 provides a path for one plate of the parasiticcapacitance between the conductor 240 and the substrate 210 to be tiedto a ground potential. Thus, a path may be established to shuntinterfering coupling due to high transient events to the referencepotential.

As indicated above, the current sensor 200 may be similar to the currentsensor 100 described above with respect to FIG. 1, however, the currentsensor 200 may have direct bonding. For example, a first interconnect260 a may be used to couple the via 250 to at least one signal lead 245and a second interconnect 260 b may be used to couple the second surface210 b of the semiconductor substrate 210 to at least one signal lead245. In some embodiments, the via 250 and the second surface 210 b maybe coupled to the same signal lead 245. In other embodiments, the via250 and the second surface 210 b may be coupled to different signalleads 245. Thus separate wires (i.e. interconnects 260 a, 260 b) may bemaintained to a reference potential (i.e. ground plane).

In an embodiment, the insulation layer 230 may be applied or coated to afirst surface of the conductor 240. The insulation layer 230 may bedisposed on the first surface such that it covers the entire firstsurface of the conductor 240. In some embodiments, the insulation layer230 may be larger (e.g. width, length) than the conductor 240. A largerinsulation layer 230 may provide further isolation between secondarycircuitry including the magnetic field sensing element 215 and theconductor 240. For example, the insulation layer 230 may be larger (e.g.width, length) than the conductor 240 for creepage and clearancereasons. In some embodiments, to meet a specific standard or need of aparticular application of the current sensor 200, the insulation layer230 may extend beyond a length of the conductor 240, shield layer 220and/or substrate 210 to meet a clearance and/or creepage requirement andincrease a distance between two conductive parts (e.g., conductor 240,substrate 210) of the current sensor 200. The length or distance bywhich the insulation layer 230 extends beyond a length of the conductor240, shield layer 220 and/or substrate 210 may vary based on aparticular application.

For example, the insulation layer 230 may have at least one edge 230 c,230 d that that extends beyond an edge 240 c, 240 d of the conductor240. In some embodiments, both a first edge 230 c of the insulationlayer 230 extends beyond a first edge 240 c of the conductor 240 and asecond edge 230 d of the insulation layer 230 extends beyond second edge240 d of the conductor 240. In an embodiment, the extended edges 230 c,230 d of the insulation layer 230 may provide further protection(isolation) between secondary and primary sides of the current sensor.

Now referring to FIG. 3, a current sensor 300 is provided with a shieldlayer 320 to reduce the effects of electrical, voltage, or electricaltransient noise coupled to the active circuitry through the parasiticcapacitance between a conductor 340 and the circuitry. The currentsensor 300 includes a conductor 340, an insulation layer 330 in contactwith the conductor 340 and a semiconductor substrate 310 having a shieldlayer 320 disposed on a first surface 310 a proximal to the insulationlayer 330 and a second opposing surface 310 b distal from the insulationlayer 330. The current sensor 300 further includes a magnetic fieldsensing circuit, including a magnetic field sensing element 315,supported by the semiconductor substrate 310 and a via 350 extendingthrough the semiconductor substrate 310 to couple the shield layer 320to the second surface 310 b of the semiconductor substrate 310. In anembodiment, the shield layer 320 may be coupled to a reference potential(e.g., a reference voltage, a supply voltage, a DC voltage, groundvoltage).

In an embodiment, the current sensor 300 may have a die downconfiguration. A die down configuration refers to a current sensorhaving a magnetic field sensing element 315 and associated circuitry ona surface (here on a bottom, first surface 310 a) of the substrate 310proximal to the current conductor 340. For example, in the illustrativeembodiment of FIG. 3, the semiconductor substrate 310 has a firstsurface 310 a disposed proximal to the conductor 340 and a secondsurface 310 b distal to the conductor 340. The magnetic field sensingelement 315 may be disposed along the first surface 310 a and thusproximal from the conductor 340. In some embodiments, the first surface310 a may be referred to as an active surface. A die down assembly maybe used in current sensors, where it is important for the magnetic fieldsensing element 315 to be as close the conductor 340 as possible.

The magnetic field sensing element 315 may be diffused into the firstsurface 310 b or otherwise disposed on or supported by the first surface310 b. While only one magnetic field sensing element 315 is shown, itshould be appreciated that more than one magnetic field sensing element315 may be used in current sensor 300.

In an embodiment, the magnetic field sensing element 315 may include aHall-effect element or a magnetoresistance element. For example, themagnetoresistance elements may include at least one of Indium Antimonide(InSb), a GMR element, an AMR element, a TMR element or a MTJ element.

The current sensor 300 may be provided as an integrated circuit (IC)having a lead frame. The lead frame may have two portions, a firstportion for carrying a primary current to be detected and a secondportion for carrying signals to and from the current sensor 300. In anembodiment, the first portion of the lead frame may provide theconductor 340 and the second portion of lead frame may comprise aplurality of signal leads 345.

In an embodiment, the shield layer 320 and the insulation layer 330 canbe disposed between the magnetic field sensing element 315 (andsemiconductor substrate 310) and the conductor 340. The first surface310 a of the semiconductor substrate 310 is disposed along a firstsurface of the shield layer 320. Therefore, the magnetic field sensingelement 315 is proximal to the shield layer (with respect to the secondsurface 310 b which is distal from the shield layer 320). In someembodiment, this type of shielding may be referred to as top metalshielding as the magnetic field sensing element 315 and the active firstsurface 310 a are proximal to the shield layer 320.

The shield layer 320 may be applied to or otherwise coated on the firstsurface 310 a of the substrate 310. For example, the shield layer 320may be plated to the first surface 310 a. In other embodiments, theshield layer 320 may be disposed on the insulation layer 330 and thesubstrate 310 may be disposed on the shield layer 320. The insulationlayer 330 may be applied or otherwise coated to a first surface of theconductor 340. In an embodiment, the shield layer 320 may be applied tothe substrate 310 and the insulation layer 330 may be applied to theconductor 340 as initial steps in a manufacturing process of currentsensor 300. Thus, the shield layer 320 may be applied or attached to theinsulation layer 330 to couple the substrate 310 to the conductor 340.

In some embodiments, to limit the amount of eddy currents forming in theshield layer 320, the shield layer 320 may include an aperture, hole, oropening 370 (e.g., a slot, slit, cut, cross shape opening or any othertype of opening to aid in the reduction of eddy currents which mayaffect magnetic field sensing element 315). For example, and referringbriefly to FIG. 3A, a slit 370 can be formed into the shield layer 320such that the slit 370 is generally aligned with the magnetic fieldsensing element 315. In some embodiments, slit 370 may be formed suchthat is not generally aligned (e.g., not centered) or positioned overmagnetic field sensing element 315.

In FIG. 3A, a bottom surface of the shield layer 320 is shown. The slit370 may be formed as a cross shape having a center open region thatexposes the magnetic field sensing element 315 to the insulation layer330 and conductor 340 under the insulation layer 330. In someembodiments, the slit 370 may have the same dimensions (e.g., length,width) as the magnetic field sensing element 315. In other embodiments,the slit 370 may have different dimensions (e.g., smaller dimensions,larger dimensions) than the magnetic field sensing element 315. Forexample, and as shown in FIG. 3A, the slit 370 may be formed as a crossshape having a center open region that exposes the magnetic fieldsensing element 315 to the insulation layer 330 and conductor 340 underthe insulation layer 330. In some embodiments, connections 371 may beformed at the edges of the shield layer 320 such that the slots or slitsor openings 372, 370, 376, 374 are open and/or no conductor portionconnects these regions over the magnetic field sensing element 315.

In the illustrative embodiment of FIG. 3A, the shield layer 320 includesfour portions 380-386 separated by four slits 370-376. The four portions380-386 can be coupled with a conductive region 378. A bonding pad 398may be provided to allow the shield layer 320 to be coupled to areference potential. In some embodiments, a connection may be made tocircuitry disposed within or on a layer of semiconductor substrate 310using standard via and/or metallization technology. In the presence of amagnetic field, it will be understood that eddy currents 390-396 can beinduced in the shield layer 320. Due to the four slits 370-376, it willbe understood that properties of a current path (i.e., a diameter or apath length) of the closed looped eddy currents 390-396 can be altered.For example, slits 370-376 may be formed such that the diameter of eddycurrents paths 390-396, in an area of magnetic field sensing element315, may be reduced. In some embodiments, responsive to a reduction ofeddy currents 390-396, a vector or a direction of a magnetic field nearmagnetic field sensing element 315 may be changed. Thus, an effectivefield from any eddy current 390-396 as measured by magnetic fieldsensing element 315 may be lower than if the slits 370-376 were notpresent in shield layer 320. In some embodiments, slits 370-376 may beformed such that eddy currents paths 390-396 are eliminated.

It will be understood that the reduced size of the closed loops in whichthe eddy currents 390-396 travel results in smaller eddy currents390-396 and a smaller local effect on the AC magnetic field that inducedthe eddy current. Therefore, the sensitivity of the current sensor 300on which the magnetic field sensing element 315 and the shield layer 320are used is less affected by the smaller eddy currents 390-396.Furthermore, by placing the shield layer 320 in relation to the magneticfield sensing element 315 as shown, so that the slits 370-376 pass overthe magnetic field sensing element 315, it will be understood that themagnetic field associated with any one of the eddy currents 390-396,tends to form magnetic fields passing through the magnetic field sensingelement 315 in two directions, canceling over at least a portion of thearea of the magnetic field sensing element 315. It will also beappreciated that other shapes, sizes, and configurations of one or moreslits in the shield layer 320 are possible, such as those shown in U.S.Pat. No. 7,598,601, entitled “Current Sensor,” issued on Oct. 6, 2009,assigned to the assignee of the subject application and incorporatedherein by reference.

Referring back to FIG. 3, the via 350 may be formed in the semiconductorsubstrate 310. The via 350 may be a through-silicon via and extend fromthe first surface 310 a to the second surface 310 b of the semiconductorsubstrate 310. An interconnect 360 may electrically couple the via 350to at least one of the signal leads 345. In some embodiments, the shieldlayer 320 can be coupled to a reference potential (e.g., a referencevoltage, a supply voltage, a DC voltage, ground voltage) through the via350.

Now referring to FIG. 4, a current sensor 400 having a dual dieassembly, also referred herein as a stacked die assembly, is provided.The current sensor 400 includes a conductor 440, a first die 470 havinga first surface proximal to the conductor 440 and a second opposingsurface distal from the conductor 440 and a second die 480 having afirst surface 410 a proximal to the first die 470 and a second opposingsurface 410 b distal from the first die 470 and supporting a magneticfield sensing circuit. In an embodiment, the first die 470 may include ashield layer 430 and as will be described in greater detail below, thefirst die 470 may operate as an insulation layer and/or a shieldinglayer for the second die 480.

In an embodiment, the current sensor 400 can be an IC having a leadframe. The lead frame may have two portions, a first portion forcarrying a primary current to be detected and a second portion forcarrying signals to and from the current sensor. In an embodiment, thefirst portion may provide the conductor 440 and the second portion mayinclude a plurality of signal leads 445.

The first die 470 may include a substrate 438, a shield layer 430 havinga first surface proximal to the second surface of the substrate 438 anda protective layer 420 having a first surface proximal to the secondsurface of the shield layer and having a second opposing surface.

In some embodiments, the first die may include a first insulation layer434 having a first surface proximal to the second surface of thesubstrate 438 and having a second opposing surface. The first insulationlayer 434 may be disposed between the shield layer 430 and the substrate438. In other embodiments, the substrate 438 may be an insulatingsubstrate and the first insulation layer 434 may not be necessary. Insome embodiments, an additional insulating layer may be disposed on orotherwise formed on a backside of substrate 438 such that there is aninsulating layer between substrate 438 and the conductor 440. Theadditional layer and first insulation layer 434 may include thermaloxide, an LPCVD nitride or oxide, oxide and nitride layers, or otherinsulating material suitable for a semiconductor process.

The protective layer 420 may include a polymer dielectric material(e.g., polyimide material) or benzo-cyclobutene (BCB). The shield layer430 can be disposed over a surface of the protective layer 420. Forexample, the shield layer 430 may be applied to or otherwise coated on asurface of the protective layer 420. In other embodiments, theprotective layer 420 may be applied or otherwise coated on a surface ofthe shield layer 430.

The shield layer 430 may include copper, aluminum or other types ofconductive metal materials. In some embodiments, the shield layer 430may be applied to or otherwise coated on a first surface of thesubstrate 438. In other embodiments, the shield layer 430 may be appliedto otherwise coated on a first surface of the insulation layer 434,which is disposed on the first surface of the substrate 438.

The insulation layer 434 can be disposed over a first surface of thesubstrate 438. The insulation layer 434 may be applied or coated to thefirst surface of the substrate 438. The insulation layer 434 may includesilicon oxide, silicon dioxide or a combination of both. In someembodiments, the substrate 438 may include a semiconductor material,such as a silicon wafer. In other embodiments, the substrate 438 may bean insulating substrate and include materials such as Alumina or glass.

In some embodiments, a length of the shield layer 430 may be less than alength of the first die 470 (e.g., the shield layer 430 may not extendthe full length of the first die 470, also as illustrated in FIG. 5).For example, the first die 470 may have a length defined by a first andsecond edge. The shield layer 430 may not extend to one of the firstedge, second edge or both. In an embodiment, the shield layer 430 may bethe same length as the second die 480 and positioned under the seconddie 480. In other embodiments, the length of the shield layer 430 may belarger than the length of the second die, for example, to allow theshield layer 430 to be bonded to the reference potential though theaperture 424 in the protective layer 420. In an embodiment, in which theshield layer 430 does not extend a full length of the first die 470, oneor more portions of insulation material may be deposited on either orboth edges of the shield layer 430 to extend that layer in the stack thefull length of the first die 470.

In an embodiment, an aperture, hole, or opening 424 may be formed intothe protective layer 420. A bond pad 426 may be disposed in the aperture424. The bond pad 426 may be in contact with the shield layer 430through the aperture 424 to electrically couple the shield layer 430 toat least one of the signal leads 445 through an interconnect 460 c. Theinterconnect 460 c may be a wire bond. In some embodiments, the bond pad426 is a ground pad that is coupled to a ground signal lead 445 of thecurrent sensor 400. Thus, the shield layer 430 can be coupled to areference potential (e.g., a reference voltage, a supply voltage, a DCvoltage, ground voltage).

The second die 480 may include a substrate 410 having a first surface410 a and a second surface 410 b. The substrate 410 may be asemiconductor material. A magnetic field sensing circuit 415 andassociated circuitry may be disposed along the second surface 410 b. Themagnetic field sensing circuit 415 may include an integrated circuit(IC), having at least one magnetic field transducer or sensing element(e.g., a Hall-effect element, magnetoresistance element, giantmagnetoresistance element and interface circuitry (not shown)) of amagnetic field sensor provided therein. The substrate 410 may be asemiconductor material or an insulating substrate.

In an embodiment, the magnetic field sensing element 415 may include aHall-effect element or a magnetoresistance element. For example, themagnetoresistance elements may include at least one of Indium Antimonide(InSb), a GMR element, an AMR element, a TMR element or a MTJ element.The magnetic field sensing element 415 may be diffused into the secondsurface 410 b or otherwise disposed on or supported by the secondsurface 410 b. While only one magnetic field sensing element 415 isshown, it should be appreciated that more than one magnetic fieldsensing element 415 may be used in current sensor 400.

In an embodiment, a plurality of interconnects 460 a-460 b mayelectrically couple the second surface 410 b to at least one signal lead445. In some embodiments, the interconnects 460 a-460 b may be coupledto the second surface 410 b. The interconnects 460 a-460 b can beconfigured to couple the magnetic field sensing circuit 415 andassociated circuitry (i.e. active circuitry) to at least one of thesignal leads 445.

In an embodiment, the first die 470 may operate as an insulation layerand/or a shielding layer for the second die 480. For example, and asillustrated in FIG. 4, the first die 470 is disposed between the seconddie 480 and the conductor 440. The first die 470 can be configured toprovide shielding and insulation (e.g. protective layer 420, shieldlayer 430) for the magnetic field sensing circuit, including a magneticfield sensing element 415, from the current carrying conductor 440.Thus, in an embodiment, the current sensor 400 can have a groundedshield layer 430 in a die up assembly without using vias, such as thoseused in the current sensors 100, 200, 300 described above with respectto FIGS. 1-3.

In some embodiments, the length of a layer in current sensor 400 (e.g.,length of first die 470, second die 480, insulation layer 434) may beselected relative to another layer based on creepage and clearanceconsiderations. For example, in some embodiments, to meet a specificstandard or need of a particular application of the current sensor 400,the first die 470 may be larger (in terms of length or width) than theconductor 440 and/or the second die 480 to meet a clearance and/orcreepage requirement and increase a distance between two conductiveparts of the current sensor 400. The length or distance by which thefirst die 470 extends beyond a length of the second die 480 and/orconductor 440 may vary based on a particular application. For example, afirst edge and/or a second edge of the first die 470 may extend past afirst edge and/or second edge of the conductor 440, the second die 480or both.

Now referring to FIG. 5, a current sensor 500 having a dual dieassembly, also referred herein as a stacked die assembly, is provided.The current sensor 500 includes a conductor 540, a first die 570 havinga first surface proximal to the conductor 540 and a second opposingsurface distal from the conductor 540 and a second die 580 having afirst surface 510 a proximal to the first die 570 and a second opposingsurface 510 b distal from the first die 570 and supporting a magneticfield sensing circuit. In an embodiment, the first die 570 may include ashield layer 530 and as will be described in greater detail below, thefirst die 570 may operate as an insulation layer and/or a shieldinglayer for the second die 580.

In an embodiment, current sensor 500 may be similar to current sensor400 described above with respect to FIG. 4, as in current sensor 500 hasa dual die (e.g. first die 570, second die 580) assembly. However,current sensor 500 may further include a second insulation layer 538 inthe first die 570.

In an embodiment, the current sensor 500 can be provided in the form ofan IC having a lead frame. The lead frame may have two portions, a firstportion for carrying a primary current to be detected and a secondportion for carrying signals to and from the current sensor. In anembodiment, the first portion may provide the conductor 540 and thesecond portion may include a plurality of signal leads 545.

The first die 570 may include a substrate 536, a shield layer 530 havinga first surface proximal to the second surface of the substrate 538 anda protective layer 520 having a first surface proximal to the secondsurface of the shield layer and having a second opposing surface.

In some embodiments, the first die may include a first insulation layer534 having a first surface proximal to the second surface of thesubstrate 530 and having a second opposing surface. The first insulationlayer 534 may be disposed between the shield layer 530 and the substrate538. In some embodiments, the first insulation layer 534 may include oneor more layers of insulation. The one or more layers of the firstinsulation layer 534 may include different materials. In otherembodiments, each of the multiple first insulation layers 534 mayinclude the same materials. In some embodiments, the substrate 538 maybe an insulating substrate and the first insulation layer 534 may not benecessary.

The first die 570 may include a second insulation layer 538 disposedbetween the conductor 540 and the substrate 536. The second insulationlayer 538 may be applied or coated to a surface of the substrate 536. Inother embodiments, the second insulation layer 538 may be applied orcoated to a surface of the conductor 540 and the substrate 536 may bedisposed over a first surface of the second insulation layer 538. Thus,the second insulation layer 538 may be disposed over the second surfaceof the substrate 536 or the first surface of the conductor 540.

In an embodiment, the protective layer 520 may include a polymerdielectric material or benzocyclobutene (BCB). The shield layer 530 maybe applied to a surface of the protective layer 520. In otherembodiments, the protective layer 520 may be applied or coated over asurface of the shield layer 530. In some embodiments, protective layer520 may include a PECVD oxide, nitride and alumina combination (e.g.,aluminum oxide). In one embodiment, protective layer 520 may include aPECVD oxide, nitride and alumina combination (e.g., aluminum oxide) incombination with BCB and/or PI (polyimide).

In an embodiment, the shield layer 530 may be disposed over a firstsurface of the first insulation layer 534. For example, the shield layer530 may be applied or coated over the first surface of the firstinsulation layer 534. The shield layer 530 may include copper, aluminumor other types of conductive metal materials.

The first insulation layer 534 can be disposed over a first surface ofthe substrate 536. The first insulation layer 534 may be applied orcoated over the first surface of the substrate 536. In otherembodiments, the first insulation layer 534 may be applied to a surfaceof the shield layer 530 and then disposed on the substrate 536. Thefirst insulation layer 534 may include silicon oxide, silicon dioxide ora combination of both. The substrate 536 may include a semiconductormaterial, such as a silicon wafer. In other embodiments, the substrate536 may be an insulating substrate and include materials such as Aluminaor glass.

In an embodiment, the second insulation layer 538 may include a polymerdielectric material. For example, the polymer dielectric material mayinclude at least one of BCB, a polyimide material, or a layer ofadhesive. In some embodiments, the second insulation layer 538 mayinclude a flex circuit having a layer of Kapton® and a metalized layer.

In some embodiments, the first die 570 may include a flex circuit. Forexample, the flex circuit may include a first layer of Kapton®, ametalized layer disposed over the first layer of Kapton®, a second layerof Kapton® disposed over the metallization layer and a third insulationlayer disposed over the second layer of Kapton®.

In an embodiment, an aperture, hole, or opening 524 may be formed intothe protective layer 520. A bond pad 526 may be disposed in the aperture524. The bond pad 526 may be in contact with the shield layer 530through the aperture 524 to electrically couple the shield layer 530 toat least one of the signal leads 545 through an interconnect 560 c. Theinterconnect 560 c may be a wire bond. In some embodiments, the bond pad526 is a ground pad that is coupled to a ground signal lead 545 of thecurrent sensor 500. Thus, the shield layer 530 can be coupled to areference potential (e.g., a reference voltage, a supply voltage, a DCvoltage, ground voltage).

The second die 580 may include a substrate 510 having a first surface510 a and a second surface 510 b. The substrate 510 may be asemiconductor material or an insulating substrate. A magnetic fieldsensing element 515 and associated circuitry may be disposed along thesecond surface 510 b. In an embodiment, the magnetic field sensingelement 515 may include a Hall-effect element or a magnetoresistanceelement. For example, the magnetoresistance elements may include atleast one of Indium Antimonide (InSb), a GMR element, an AMR element, aTMR element or a MTJ element.

The magnetic field sensing element 515 may be diffused into the secondsurface 510 b or otherwise disposed on or supported by the secondsurface 510 b. While only one magnetic field sensing element 515 isshown, it should be appreciated that more than one magnetic fieldsensing element 515 may be used in current sensor 500.

In an embodiment, a plurality of interconnects 560 a-560 b mayelectrically couple the second surface 510 b to at least one signal lead545. In some embodiments, the interconnects 560 a-560 b may be coupledto the second surface 510 b. In an embodiment, bond pads may be disposedon the second surface 610 b to couple to the interconnects 560 a-560 b.The interconnects 560 a-560 b can be configured to couple the magneticfield sensing element 515 (i.e. active circuitry) to at least one of thesignal leads 545.

In the illustrative embodiment of FIG. 5, current sensor 500 includesthe second insulation layer 538 in the first die 570. The secondinsulation layer 538 may include one or more layers of insulation. In anembodiment, the one or more layers of the second insulation layer 538may include different materials. In other embodiments, each of themultiple second insulation layers 538 may include the same materials.

In an embodiment, the second insulation layer 538 may provide a secondlayer of voltage isolation for the magnetic field sensing element 515from the conductor 540. For example, the first die 570 may operate as aninsulation layer and/or a shielding layer for the second die 580. Thefirst die 570 is disposed between the second die 580 and the conductor540. The first die 570 can be configured to provide multiple layers ofshielding and/or insulating (e.g. protective layer 520, shield layer530, first insulation layer 534, second insulation layer 538) for themagnetic field sensing element 515 from the current carrying conductor540. In some embodiments, the second insulation layer 538 may bereferred to as a wafer backside coating.

In some embodiments, the first die 570 may be larger (e.g. width,length) than the conductor 540 and/or the second die 580. The length ofa layer in current sensor 500 (e.g., length of first die 570, second die580) may be selected relative to another layer based on creepage andclearance considerations. For example, the first die 570 may have atleast one edge 570 a, 570 b that extends beyond an edge 540 c, 540 d ofthe conductor 540 and/or an edge 580 a, 580 b of the second die 580. Insome embodiments, both a first edge 570 a of the first die 570 extendsbeyond a first edge 540 c of the conductor 540 and a second edge 570 bof the first die 570 extends beyond second edge 540 b of the conductor540. A first edge 570 a of the first die 570 may extend beyond a firstedge 580 a of the second die 580 and a second edge 570 b of the firstdie 570 may extend beyond a second edge 580 b of the second die 580.

In an embodiment, to meet a specific standard or need of a particularapplication of the current sensor 500, the first die 570 may be larger(in terms of length or width) than the conductor 540 and/or the seconddie 580 to meet a clearance and/or creepage requirement and increase adistance between two conductive parts of the current sensor 500. In someembodiments, having the first die 570 larger than the conductor 540, thesecond die 580 or both to provide further voltage isolation for themagnetic field sensing element 515 from the conductor 540.

In an embodiment, the second edge 570 b may span a gap between thesecond edge 540 b of the conductor 540 and at least one signal lead 545.Therefore, in some embodiments, the second edge 540 b may be in contactwith at least one signal lead 545.

Now referring to FIG. 6, a current sensor 600 having a die up assemblyand with a shield layer 630 to reduce the effects of electrical,voltage, or electrical transient noise coupled to the active circuitrythrough parasitic capacitance between the conductor 640 and thecircuitry. The current sensor 600 includes a conductor 640, aninsulation layer 620 in contact with the conductor 640, a shield layer630 comprising at least one of a metalized tape or a metalized Mylar®spaced from the conductor 640 by the insulation layer 630 and asemiconductor substrate 610 having a first surface 610 a disposedproximal to the shield layer 630 and a second opposing surface 610 bdisposed distal from the shield layer 630 and supporting a magneticfield sensing element 615.

Current sensor 600 may be provided in the form of an integrated circuithaving a lead frame. The lead frame may include a first portion forcarrying a primary current and a second portion for carrying signals toand from the current sensor 600. In an embodiment, the first portion ofthe lead frame may provide the conductor 640 and the second portion maycomprise a plurality of signal leads 645 a, 645 b.

In an embodiment, the semiconductor substrate 610 may have a firstsurface 610 a disposed proximal to the shield layer 630 and a secondsurface 610 b disposed distal from the shield layer 630. A magneticfield sensing element 615 and associated circuitry may be disposed onthe second surface 610 b. Thus, the second surface 610 b may support themagnetic field sensing element 615 and associated circuitry and thecurrent sensor 600 may have a die up assembly. The magnetic fieldsensing element 615 may include at least one of a Hall-effect element ora magnetoresistance element. For example, the magnetoresistance elementmay include at least one of Indium Antimonide (InSb), a GMR element, anAMR element, a TMR element or a MTJ element.

The magnetic field sensing element 615 may be diffused into the secondsurface 610 b or otherwise disposed on or supported by the secondsurface 610 b. While only one magnetic field sensing element 615 isshown, it should be appreciated that more than one magnetic fieldsensing element 615 may be used in current sensor 600.

The shield layer 630 can be disposed between the semiconductor substrate610, having the magnetic field sensing element 615, and the insulationlayer 620. The shield layer 630 can be spaced from the conductor 640 bythe insulation layer 620 and therefore, the shield layer 630 is disposedbetween the magnetic field sensing element 615 and the current carryingconductor 640. In some embodiments, the shield layer 630 may be appliedto or otherwise coated on the first surface 610 a of the substrate 610.For example, the shield layer 630 may be plated to the first surface 610a. In other embodiments, the shield layer 630 may be disposed on theinsulation layer 620 and the substrate 610 may be disposed on the shieldlayer 630.

The shield layer 630 may include at least one of a metalized tape ormetalized Mylar®. In some embodiments, the shield layer 630 may includemultiple layers (e.g. two or more layers). For example, an adhesivelayer or a nonconductive adhesive layer may be disposed over orotherwise formed over a first surface of shield layer 630 such that isit between shield layer 630 and semiconductor substrate 610. In anembodiment, one or more of the shield layers 630 may include differentmaterials. In other embodiments, each of the multiple shield layers 630may include the same materials.

In an embodiment, current sensor 600 may have a floating shield layer630 (e.g. not grounded). For example, the shield layer 630 may not becoupled to a reference potential (e.g., a reference voltage, a supplyvoltage, a DC voltage, ground voltage) or signal leads 645 a, 645 b.

The insulation layer 620 may be applied or coated to a surface of theconductor 640. In an embodiment, the substrate 610 may be mounted orotherwise disposed on the conductor 640. The substrate 610 may bemounted after the shield layer 630 has been applied to the first surface610 a and after the insulation layer 620 has been applied to the firstsurface of the conductor 640. Thus, the shield layer 630 can be mountedon or otherwise disposed on the insulation layer 620 and make contactwith the insulation layer 620. In an embodiment, the substrate 610 maybe separated from the conductor 640 by at least the shield layer 630 andthe insulation layer 620.

Now referring to FIG. 7, a current sensor 700 having a die up assemblyand with a shield layer 730 to reduce the effects of electrical,voltage, or electrical transient noise coupled to the active circuitrythrough parasitic capacitance between the conductor 740 and thecircuitry. The current sensor 700 includes a conductor 740, aninsulation layer 720 in contact with the conductor 740, a shield layer730 comprising at least one of a metalized tape or a metalized Mylar®spaced from the conductor 740 by the insulation layer 730 and asemiconductor substrate 710 having a first surface 710 a disposedproximal to the shield layer 730 and a second opposing surface 710 bdisposed distal from the shield layer 730 and supporting a magneticfield sensing element 715.

Current sensor 700 may be provided in the form of an integrated circuithaving a lead frame. The lead frame may include a first portion forcarrying a primary current and a second portion for carrying signals toand from the current sensor 700. In an embodiment, the first portion ofthe lead frame may provide the conductor 740 and the second portion maycomprise a plurality of signal leads 745 a, 745 b.

The semiconductor substrate 710 may have a first surface 710 a disposedproximal to the shield layer 730 and a second surface 710 b disposeddistal from the shield layer 730. A magnetic field sensing element 715may be disposed long the second surface 710 b. Thus, the second surface710 b may support the magnetic field sensing element 715 and associatedcircuitry (i.e. magnetic field sensing circuit) and the current sensor700 has a die up assembly.

The magnetic field sensing element 715 may include at least one of aHall-effect element or a magnetoresistance element. For example, themagnetoresistance element may include at least one of Indium Antimonide(InSb), a GMR element, an AMR element, a TMR element or a MTJ element.The magnetic field sensing element 715 may be diffused into the secondsurface 710 b or otherwise disposed on or supported by the secondsurface 710 b. While only one magnetic field sensing element 715 isshown, it should be appreciated that more than one magnetic fieldsensing element 715 may be used in current sensor 700.

As illustrated in FIG. 7, the shield layer 730 is disposed between thesemiconductor substrate 710, having the magnetic field sensing element715, and the insulation layer 720. In some embodiments, this may bereferred to as a backside die shield, as the first surface 710 a distalfrom the magnetic field sensing element 715 is coated with the shieldlayer 730. The shield layer 730 may be applied to or otherwise coated onthe first surface 710 a of the substrate 710. For example, the shieldlayer 730 may be plated to the first surface 710 a. In otherembodiments, the shield layer 730 may be disposed on the insulationlayer 720 and the substrate 710 may be disposed on the shield layer 720.

The shield layer 730 may include at least one of a metalized tape ormetalized Mylar®. In some embodiments, the shield layer 730 may includemultiple layers (e.g. two or more layers). For example, an adhesivelayer or a nonconductive adhesive layer may be disposed over orotherwise formed over a first surface of shield layer 730 such that isit between shield layer 730 and semiconductor substrate 710. In anembodiment, one or more of the shield layers 730 may include differentmaterials. In other embodiments, each of the multiple shield layers 730may include the same materials.

The shield layer 730 can be spaced from the conductor 740 by theinsulation layer 720 and therefore, the shield layer 730 can be disposedbetween the magnetic field sensing element 715 and the current carryingconductor 740. The insulation layer 720 may be applied or coated to asurface of the conductor 740. In an embodiment, the substrate 710 may bemounted or otherwise disposed on the conductor 740. The substrate 710may be mounted after the shield layer 730 has been applied to the firstsurface 710 a and after the insulation layer 720 has been applied to thefirst surface of the conductor 740. Thus, the shield layer 730 can bemounted on or otherwise disposed on the insulation layer 720 and makecontact with the insulation layer 720.

Current sensor 700 may be different from current sensor 600 describedabove with respect to FIG. 6, in that the shield layer 730 is coupled toat least one signal lead 745 a. For example, an interconnect 760 maycouple the shield layer 730 to at least one signal lead 745 a. A firstbond pad 726 a (or connection area as it may not be a patterned pad) maybe disposed on the first surface of the shield layer 730 and a secondbond pad 726 b may be disposed on a first surface of the signal lead 745a. The interconnect 760 may be coupled to both the first bond pad 726 aand the second bond pad 726 b. The interconnect 760 may include a wirebond. In an embodiment, the shield layer 730 may be coupled to areference potential (e.g., a reference voltage, a supply voltage, a DCvoltage, ground voltage) through the interconnect 760. Thus, inoperation, the shield layer 730, which is electrically coupled to areference potential, serves to tie one place of undesirable parasiticcapacitance between the conductor 740 and substrate 710 to the referencepotential (e.g., ground).

Now referring to FIG. 8, a current sensor 800 having a die up assemblyand with a shield layer 830 to reduce the effects of electrical,voltage, or electrical transient noise coupled to the active circuitrythrough parasitic capacitance between the conductor 840 and thecircuitry. The current sensor 800 includes a conductor 840, aninsulation layer 820 in contact with the conductor 840, a shield layer830 comprising at least one of a metalized tape or a metalized Mylar®spaced from the conductor 840 by the insulation layer 830 and asemiconductor substrate 810 having a first surface 810 a disposedproximal to the shield layer 830 and a second opposing surface 810 bdisposed distal from the shield layer 830 and supporting a magneticfield sensing element 815.

Current sensor 800 may be provided in the form of an integrated circuithaving a lead frame. The lead frame may include a first portion forcarrying a primary current and a second portion for carrying signals toand from the current sensor 800. In an embodiment, the first portion ofthe lead frame may provide the conductor 840 and the second portion maycomprise a plurality of signal leads 845 a, 845 b.

The semiconductor substrate 810 may have a first surface 810 a disposedproximal to the shield layer 830 and a second surface 810 b disposeddistal from the shield layer 830. A magnetic field sensing element 815may be disposed long the second surface 810 b. Thus, the second surface810 b may support the magnetic field sensing element 815 and associatedcircuitry (i.e. magnetic field sensing circuit) and the current sensor800 has a die up assembly. The magnetic field sensing element 815 mayinclude at least one of a Hall-effect element or a magnetoresistanceelement. For example, the magnetoresistance element may include at leastone of Indium Antimonide (InSb), a GMR element, an AMR element, a TMRelement or a MTJ element.

The magnetic field sensing element 815 may be diffused into the secondsurface 810 b or otherwise disposed on or supported by the secondsurface 810 b. While only one magnetic field sensing element 815 isshown, it should be appreciated that more than one magnetic fieldsensing element 815 may be used in current sensor 800.

As illustrated in FIG. 8, the shield layer 830 is disposed between thesemiconductor substrate 810, having the magnetic field sensing element815, and the insulation layer 820. In some embodiments, this may bereferred to as a backside die shield, as the first surface 810 a distalfrom the magnetic field sensing element 815 is coated with the shieldlayer 830. The shield layer 830 may be applied to or otherwise coated onthe first surface 810 a of the substrate 810. For example, the shieldlayer 830 may be plated to the first surface 810 a. In otherembodiments, the shield layer 830 may be disposed on the insulationlayer 820 and the substrate 810 may be disposed on the shield layer 820.

In an embodiment, the shield layer 830 may include at least one of ametalized tape or metalized Mylar®. In some embodiments, the shieldlayer 830 may include multiple layers (e.g. two or more layers). In anembodiment, one or more of the shield layers 830 may include differentmaterials. In other embodiments, each of the multiple shield layers 830may include the same materials.

The shield layer 830 can be spaced from the conductor 840 by theinsulation layer 820 and therefore, the shield layer 830 can be disposedbetween the magnetic field sensing element 815 and the current carryingconductor 840. In operation, the shield layer 830, which is electricallycoupled to a reference potential, serves to tie one place of undesirableparasitic capacitance between the conductor 840 and substrate 810 to thereference potential (e.g., ground).

The insulation layer 820 may be applied or coated to a surface of theconductor 840. In some embodiments, such as during a manufacturingprocess of current sensor 800, the substrate 810 may be mounted orotherwise disposed on the conductor 840. The substrate 810 may bemounted after the shield layer 830 has been applied to the first surface810 a and after the insulation layer 820 has been applied to the firstsurface of the conductor 840. Thus, the shield layer 830 can be mountedon or otherwise disposed on the insulation layer 820 and make contactwith the insulation layer 820.

Current sensor 800 may be different from current sensor 600 describedabove with respect to FIG. 6 and current sensor 700 described above withrespect to FIG. 7, in that a via 850 is formed within the semiconductorsubstrate 810. In some embodiments, the via 850 may be a through-siliconvia and can extend through the semiconductor substrate 810, from thefirst surface 810 a to the second surface 810 b. The via 850 may couplethe shield layer 830 to the second surface 810 b of the semiconductorsubstrate 810. In some embodiments, a conductive adhesive, a conductivesolder or like material may be sued to couple the shield layer 830 tothe second surface 810 b of the semiconductor substrate 810.

In some embodiments, an interconnect 860 may couple the via 850 to atleast one signal lead 845 a. For example, a first bond pad 826 a can bedisposed on the second surface 810 b and a second bond pad 826 b can bedisposed on a first surface of the signal lead 845. The interconnect 860can be coupled to both the first bond pad 826 a and the second bond pad826 b to couple the via 850 to the signal lead 845 a.

In an embodiment, the via 850 can be coupled to a reference potential(e.g., a reference voltage, a supply voltage, a DC voltage, groundvoltage) through the interconnect 860. In some embodiments, the shieldlayer 830 can be coupled to at least one signal lead 845 a through thevia 850 and the interconnect 860.

Now referring to FIG. 9, a current sensor 900 having a die up assemblyand with a shield layer 930 to reduce the effects of electrical,voltage, or electrical transient noise coupled to the active circuitrythrough parasitic capacitance between the conductor 940 and thecircuitry. The current sensor 900 includes a conductor 940, aninsulation layer 920 in contact with the conductor 940, a shield layer930 comprising at least one of a metalized tape or a metalized Mylar®spaced from the conductor 940 by the insulation layer 930 and asemiconductor substrate 910 having a first surface 910 a disposedproximal to the shield layer 930 and a second opposing surface 910 bdisposed distal from the shield layer 930 and supporting a magneticfield sensing element 915.

The current sensor 900 may include a conductive epoxy layer 950 disposedover a first surface of the shield layer 930. Thus, the conductive epoxylayer 950 may be disposed between the shield layer 930 and the substrate910. In some embodiments, the conductive epoxy layer 950 may be formedalong at least one side or edge surface of the substrate 910.

Current sensor 900 may be provided in the form of an integrated circuithaving a lead frame. The lead frame may include a first portion forcarrying a primary current and a second portion for carrying signals toand from the current sensor 900. In an embodiment, the first portion ofthe lead frame may provide the conductor 940 and the second portion maycomprise a plurality of signal leads 945 a, 945 b.

The semiconductor substrate 910 may have a first surface 910 a disposedproximal to the shield layer 930 and a second surface 910 b disposeddistal from the shield layer 930. A magnetic field sensing element 915may be disposed long the second surface 910 b. Thus, the second surface910 b may support the magnetic field sensing element 915 and associatedcircuitry (i.e. magnetic field sensing circuit) and the current sensor900 has a die up assembly. The magnetic field sensing element 915 mayinclude at least one of a Hall-effect element or a magnetoresistanceelement. For example, the magnetoresistance element may include at leastone of Indium Antimonide (InSb), a GMR element, an AMR element, a TMRelement or a MTJ element.

The magnetic field sensing element 915 may be diffused into the secondsurface 910 b or otherwise disposed on or supported by the secondsurface 910 b. While only one magnetic field sensing element 915 isshown, it should be appreciated that more than one magnetic fieldsensing element 915 may be used in current sensor 900.

The shield layer 930 is disposed between the conductive epoxy layer 950and the insulation layer 920. The shield layer 930 may be applied to orotherwise coated on a first surface of the conductive epoxy layer 950.In other embodiments, the shield layer 930 may be disposed on theinsulation layer 920 and the conductive epoxy layer 950 may be disposedon the shield layer 930.

The shield layer 930 can be spaced from the conductor 940 by theinsulation layer 1020 and can be spaced from the semiconductor substrate910 (having the magnetic field sensing element 915) by the conductiveepoxy layer 950, thus the shield layer 930 can be disposed between themagnetic field sensing element 915 and the current carrying conductor940. In operation, the shield layer 930, which is electrically coupledto a reference potential, serves to tie one place of undesirableparasitic capacitance between the conductor 940 and substrate 910 to thereference potential (e.g., ground).

The shield layer 930 may include at least one of a metalized tape ormetalized Mylar®. In some embodiments, the shield layer 930 may includemultiple layers (e.g. two or more layers). In an embodiment, one or moreof the shield layers 930 may include different materials. In otherembodiments, each of the multiple shield layers 930 may include the samematerials.

The insulation layer 920 may be applied or coated to a surface of theconductor 940. In some embodiments, such as during a manufacturingprocess of current sensor 900, the substrate 910 may be mounted orotherwise disposed on the conductor 940. The substrate 910 may bemounted after the shield layer 930 has been applied to the first surface910 a and after the insulation layer 920 has been applied to the firstsurface of the conductor 940. Thus, the shield layer 930 can be mountedon or otherwise disposed on the insulation layer 920 and make contactwith the insulation layer 920.

In some embodiments, an interconnect 960 may electrically couple thesecond surface 910 b to at least one signal lead 945 a. For example, afirst bond pad 926 a can be disposed on the second surface 910 b and asecond bond pad 926 b can be disposed on a first surface of the signallead 945. The interconnect 960 can be coupled to both the first bond pad926 a and the second bond pad 926 b to couple the second surface 910 bto the signal lead 945 a.

Current sensor 910 may be different from current sensor 800 describedabove with respect to FIG. 8, in that it includes the conductive epoxylayer 950 and no via. The conductive epoxy layer 950 may be formed onone or more surfaces of the semiconductor substrate 910. For example, inthe illustrative embodiment of FIG. 9, the conductive epoxy layer 950 isformed a long the first surface 910 a and one side surface 910 d. Inother embodiment, the conductive epoxy layer 950 may be formed on onlyone surface or alternatively on two or more surfaces (including sidesurfaces) of the semiconductor substrate 910.

The conductive epoxy layer 950 may include at least one of a conductivedie attach epoxy or a metallized tape. In some embodiments, theinterconnect 960 may couple the conductive epoxy layer 950 to at leastone signal lead 945 a.

Now referring to FIG. 10, a current sensor 1000 includes a first die1070 having a first surface 1075 a and a second opposing surface 1075 bsupporting a conductor 1045 in the form of a coil and a second die 1005having a first surface on which a shield layer 1060 is formed and asecond opposing surface. In an embodiment, the shield layer 1060 mayinclude a slit 1065 that may be the same as or similar to the slit shownin FIG. 3A. The shield layer 1160 may be spaced from the second surface1075 b of the first die 1070 by an airgap 1080 and the current sensormay include a magnetic field sensing element adjacent to the conductor1045 and configured as a flip chip.

As illustrated in FIG. 10, the current sensor 1000 includes a first die1070 and a second die 1005. Thus, the current sensor 1000 may have adual die or stacked die assembly. In some embodiments, and as will bedescribed in greater detail below, the first die 1070 may be aninterposer having a coil 1045 and the second die may be an IC having amagnetic field sensing element 1015.

The first die 1070 may be spaced apart from the second die 1005 by anairgap 1080 in a flip chip configuration. In an embodiment, a pluralityof solder balls or other electrical interconnect structure 1026 b-1026 cmay be disposed between respective bond pads 1026 a, 1026 d on the firstdie 1070 and on the second die 1005. In some embodiments, the pluralityof solder balls 1026 b-1026 c may be microbumps. The solder balls 1026b-1026 c may be disposed along the second surface of the first die 1070.In an embodiment, the space created by airgap 1080 may be filled with anunderfill material or an epoxy mold compound material during packaging.

The first die 1070 includes a conductor 1075 having the coil 1045. In anembodiment, the coil 1045 may have thickness that ranges from about 3 μmto about 21 μm. The conductor has a first surface 1075 a and a secondsurface 1075 b. In the illustrative embodiment of FIG. 10, the coil 1045is disposed proximal to the second surface 1075 b. A current path 1090may be formed within the conductor 1075 to couple the coil 1045 to atleast two bond pads 1026 a, 1026 d. For example, in some embodiments,the coil 1045 may be coupled to bond pads 1026 a, 1026 d.

In some embodiments, the first die 1070 may include a siliconinterposer. For example, the conductor 1075 may include a copperredistribution layer (Cu RDL) and the coil 1045 can be disposed withinthe copper redistribution layer. In an embodiment, coil 1045 may includea single copper or conductive trace.

A shield layer 1055 may be disposed along one surface (here the firstsurface 1075 a) of the conductor 1075. The shield layer 1055 may beapplied or otherwise coated on the first surface 1075 a. The shieldlayer 1055 may be provided as a back side die shield (or back sidemetallization) for the first die 1070. The shield layer 1055 may includecopper, aluminum or other conductive metal material.

The second die 1005 includes a first shield layer 1060, a protectivelayer 1010 disposed along a second surface of the first shield layer1060, a first semiconductor substrate 1020 disposed along a secondsurface of the protective layer 1010, a second semiconductor substrate1030 disposed along a second surface of the first semiconductorsubstrate 1020 and a second shield layer 1050 disposed along a secondsurface of the second semiconductor substrate 1030. In some embodiments,contacts to the different layers of second die 1005 can be made throughadditional solder balls 1026 a-1026 c and/or wire bonds (not shown) tomake an electrical connection to the magnetic field sensor and thus, tomagnetic field sensing element 1015.

In an embodiment, the protective layer 1010 may be applied or coated onthe second surface of the first shield layer 1060. The firstsemiconductor substrate 1020 may be applied or disposed on a surface ofthe protective layer 1010. In other embodiments, the protective layer1010 may be applied or coated on a surface of the first semiconductorsubstrate 1020 and the first shield layer 1060 may be applied or coatedon a surface of the protective layer 1010.

The second semiconductor substrate 1030 may be applied to a surface ofthe first semiconductor substrate 1020. The second shield layer 1050 maybe applied to or coated on a surface of the second semiconductorsubstrate 1030.

In some embodiments, the first semiconductor substrate 1020 includes ametallization layer. For example, the first semiconductor substrate 1020may include a back end of line (BEOL) metallization layer. The secondsemiconductor substrate 1030 may include a metallization layer. Forexample, the second semiconductor substrate 1030 may include a front endof line (FEOL) metallization layer. In one embodiment, the secondsemiconductor substrate 1030 may include an FEOL complementarymetal-oxide semiconductor (CMOS) wafer.

The first and second shield layers 1060, 1050 may include copper,aluminum or other conductive metal material. The second shield layer1050 may be disposed along the second surface of the secondsemiconductor substrate 1030 as a back side shield layer or back sidemetallization.

The protective layer 1010 includes a magnetic field sensing element1015. The magnetic field sensing element 1015 may include a magneticfield sensing circuit and may include at least one of a Hall-effectelement or a magnetoresistance element. For example, themagnetoresistance element may include at least one of Indium Antimonide(InSb), a GMR element, an AMR element, a TMR element or a MTJ element.In some embodiments, the magnetic field sensing element 1015 may bepositioned such that is it adjacent to or aligned with the coil 1045 inthe first die 1070.

The magnetic field sensing element 1015 may be diffused into a surfaceor otherwise disposed on or supported by a surface of the protectivelayer 1010. While only one magnetic field sensing element 1015 is shown,it should be appreciated that more than one magnetic field sensingelement 1015 may be used in current sensor 1000.

In some embodiments, the first shield layer 1060 can be disposed betweenthe protective layer 1010 (having the magnetic field sensing element1015) and the conductor 1075. The first shield layer 1060 may include aslit 1065 that may be a slot, cut or a cross shaped opening formed inthe first shield layer 1060 and that may take the various forms andprovide the advantages discussed above in connection with FIG. 3A.

In some embodiments, shield layers (e.g. first shield layer 1060, secondshield layer 1050 and third shield layer 1055) may serve to electricallytie one plate of undesirable parasitic capacitance between the conductor1075 and the first and/or second substrate 1020, 1030 to a referencepotential. The shield layers (e.g. first shield layer 1060, secondshield layer 1050 and third shield layer 1055) can be disposed along oneside of the first die 1070 and one side of the second die 1005. Thus, insome embodiments, the current sensor 1000 may have a shield layer onboth ends, the second shield layer 1050 disposed along the secondsurface of the second die 1005 and the third shield layer 1055 disposedalong the first surface of the first die 1070. In some embodiments, thismay be referred to as back side die shielding or back side metallizationwith back side shielding applied to both the first die 1070 (e.g.interposer) and the second die 1105 (e.g. MOS IC).

In some embodiments, the first die 1070 and the second die 1005 may befabricated separately to protect the circuity of the second die 1005.For example, by disposing and fabricating the coil 1045 on the first die1070 and the magnetic field sensing circuit 1015 on the second die 1005,the magnetic field sensing circuit 1015 may be protected from hightemperature processing steps, such as during dielectric and/or bufferlayer formation.

All references cited herein are hereby incorporated herein by referencein their entirety.

Having described preferred embodiments, which serve to illustratevarious concepts, structures and techniques, which are the subject ofthis patent, it will now become apparent that other embodimentsincorporating these concepts, structures and techniques may be used.Accordingly, it is submitted that the scope of the patent should not belimited to the described embodiments but rather should be limited onlyby the spirit and scope of the following claims.

What is claimed:
 1. A current sensor comprising: a conductor; a firstdie having a first surface proximal to the conductor and a secondopposing surface distal from the conductor, wherein the first diecomprises a shield layer; and a second die having a first surfaceproximal to the first die and a second opposing surface distal from thefirst die and supporting a magnetic field sensing circuit.
 2. Thecurrent sensor to claim 1, wherein the first die comprises: a substratehaving first and second opposing surfaces; a shield layer having a firstsurface proximal to the second surface of the substrate and having asecond opposing surface; and a protective layer having a first surfaceproximal to the second surface of the shield layer and having a secondopposing surface.
 3. The current sensor of claim 2, further comprising afirst insulation layer having a first surface proximal to the secondsurface of the substrate and having a second opposing surface.
 4. Thecurrent sensor of claim 2, further comprising a bond pad in contact withthe shield layer and exposed through an aperture in the protectivelayer.
 5. The current sensor of claim 2, wherein the current sensor isprovided in the form of an integrated circuit having a lead frame,wherein the conductor comprises a first portion of the lead frame and aplurality of signal leads comprise a second portion of the lead frameand wherein the current sensor further comprises a wire bond coupledbetween the bond pad and at least one of the signal leads.
 6. Thecurrent sensor of claim 2, wherein the substrate is at least one of asemiconductor substrate or an insulating substrate. The current sensorof claim 6, wherein the semiconductor substrate comprises silicon. 8.The current sensor of claim 6, wherein the insulating substratecomprises Alumina or glass.
 9. The current sensor of claim 3, whereinthe first insulation layer comprises silicon oxide, silicon dioxide, ora combination thereof
 10. The current sensor of claim 2, wherein theshield layer comprises conductive material.
 11. The current sensor ofclaim 2, wherein the protective layer comprises benzo-cyclobutene (BCB)or a polymer dielectric material.
 12. The current sensor of claim 1,wherein the magnetic field sensing circuit comprises a magnetic fieldsensing element comprising at least one of a Hall-effect element or amagnetoresistance element.
 13. The current sensor of claim 2, whereinthe first die further comprises a second insulation layer disposedbetween the conductor and the substrate.
 14. The current of sensor ofclaim 3, wherein the first insulation layer comprises one or more layersof insulation.
 15. The current sensor of claim 13, wherein the secondinsulation layer comprises a flex circuit having a layer of Kapton® anda metalized layer.
 16. The current sensor of claim 13, wherein thesecond insulation layer comprises at least one of a polymer dielectricmaterial or a layer of adhesive.
 17. The current sensor of claim 1,wherein the first die is larger than the conductor and has at least oneedge that extends beyond an edge of the conductor.
 18. The currentsensor of claim 1, wherein the first die is larger the second die andhas at least one edge that extends beyond an edge of the second die. 19.The current sensor of claim 1, wherein the first die has a lengthdefined by a first and second edge and wherein the shield layer does notextend to at least one of the first or second edge of the first die. 20.The current sensor of claim 19, wherein the current sensor is providedin the form of an integrated circuit having a lead frame, wherein theconductor comprises a first portion of the lead frame and a plurality ofsignal leads comprise a second portion of the lead frame, and whereinthe at least one edge of the first die extends beyond an edge of atleast one of the signal leads.
 21. The current sensor of claim 1,further comprising a first epoxy layer disposed between the conductorand the first surface of the first die and a second epoxy layer disposedbetween the second surface of the first die and the first surface of thesecond die.
 22. A current sensor comprising: a conductor; an insulationlayer in contact with the conductor; a shield layer comprising at leastone of a metalized tape or a metalized Mylar® spaced from the conductorby the insulation layer; and a semiconductor substrate having a firstsurface disposed proximal to the shield layer and a second opposingsurface disposed distal from the shield layer and supporting a magneticfield sensing element.
 23. The current sensor of claim 22, wherein themagnetic field sensing element comprises at least one of a Hall-effectelement or a magnetoresistance element.
 24. The current sensor of claim22, wherein the current sensor is provided in the form of an integratedcircuit having a lead frame, wherein the conductor comprises a firstportion of the lead frame and a plurality of signal leads comprise asecond portion of the lead frame.
 25. The current sensor of claim 24,further comprising a wire bond configured to couple the shield layer toat least one of the plurality of signal leads.
 26. The circuit of claim24, further comprising a via extending through the semiconductorsubstrate to couple the shield layer to the second surface of thesemiconductor substrate.
 27. The current sensor of claim 26, furthercomprising an interconnect configured to couple the via to at least oneof the plurality of signal leads.
 28. The current sensor of claim 22,further comprising a conductive epoxy disposed between the shield layerand the semiconductor substrate and along at least one side of thesemiconductor substrate between the first and second surfaces of thesubstrate.
 29. A current sensor comprising: a first die having a firstsurface and a second opposing surface supporting a conductor in the formof a coil; and a second die having a first surface on which a shieldlayer is formed and a second opposing surface, wherein the shield layercomprises an aperture configured to reduce eddy current and wherein theshield layer is spaced from the second surface of the first die by anairgap.
 30. The current sensor of claim 29, wherein the shield layercomprises a first shield layer and wherein the second die comprises: aprotective layer having a first surface proximal to the first shieldlayer and a second opposing surface; a semiconductor substrate having afirst surface proximal to the protective layer and a second opposingsurface; and a second shield layer having a first surface proximal tothe semiconductor substrate and a second opposing surface.
 31. Thecurrent sensor of claim 29, wherein the protective layer supports themagnetic field sensing element.
 32. The current sensor of claim 29,wherein the magnetic field sensing element comprises at least one of aHall-effect element or a magnetoresistance element.
 33. The currentsensor of claim 30, wherein the first die further comprises a thirdshield layer proximal to the first surface of the first die.